Manufactured locally, GilsoFlex is a dense black co-polymer blend of bitumen and gilsonite — engineered for optimal performance on New Zealand farms, commercial sites, and homes.
It is especially suited to the unique challenges of rural and coastal environments.
Biosymph Chemical Products was established in 2011 and is 100% New Zealand owned and operated. The idea for GilsoFlex came from a genuine need for better-performing sealing solutions. After extensive global research and no suitable product found, we decided to create our own.
What began with a strong vision, a deep knowledge of polymer chemistry, and a dedication to quality has grown into a trusted solution for customers nationwide.
Our founder brings extensive experience in chemical engineering and polymer science, ensuring every product we offer is grounded in solid research and high-performance chemistry.
Though initially developed for the farming sector, GilsoFlex is suitable for a wide range of industrial and domestic applications.
For exposed roofs and steel structures
GilsoFlex is a dense black, water/oil-based bituminous/gilsonite co-polymer sealer and primer paint, manufactured in New Zealand. Specially developed for local outdoorconditions, it offers outstanding protection and performance for a range of surfaces, particularly exposed roofs and steel structures.
Coverage Guide:
10 Litres covers approximately 30–50 m²
1 Litre covers approximately 3–5 m²
Coverage may vary depending on the porosity and texture of the surface.
Longevity & Maintenance:
A re-coat may be needed after 5–8 years, depending on exposure and surface condition.
Top Coat Recommendation:
While GilsoFlex finishes in a matte black, we recommend applying a lighter-coloured ClimoPlate (oil or water based) top coat over the GilsoFlex layer. This will reduce heat absorption and keeps roof surface temperatures down—ideal for sunny regions.
1. Primer, Sealer and Undercoat in one
GilsoFlex combines bitumen and gilsonite in a single sealer and paint primer product. It includes rust inhibitors, eliminating the need for a separate primer or undercoat.
2. Totally Flexible Coating
Designed to remain flexible, GilsoFlex withstands movement and distortion caused by weather conditions without cracking or breaking down.
3. Minimal Surface Preparation
GilsoFlex is non-corrosive and can be applied directly to bare steel, galvanized, powder-coated, or previously painted surfaces with minimal surface prep required.
4. Multi-Surface Application
Ideal for more than just roofs—GilsoFlex can be used on a variety of structures to seal and protect surfaces effectively.
5. Safe for Drinking Water
Water collected from roofs treated with GilsoFlex remains safe for consumption, making it suitable for rainwater harvesting systems.
6. Easy Application
GilsoFlex is a low viscosity product and not as thick as honey as most people think. The reason is the low viscosity product will penetrate small pin holes and cracks. As the product dries and cures, it slightly expand/gel and that is the sealing mechanism how GilsoFlex effectively seal and waterproofs.
GILSOFLEX 4 LITRE
Our Price: NZ$89.58 Inc GST and Delivery
Product Code: GF4
Including FREE delivery anywhere in New Zealand
GILSOFLEX 10 LITRE
Our Price: NZ$201.00 Inc GST and Delivery
Product Code: GF10
Including FREE delivery anywhere in New Zealand
GILSOFLEX 20 LITRE
Our Price: NZ$368.63 Inc GST and Delivery
Product Code: GF20
Including FREE delivery anywhere in New Zealand
Visit our website for COMBO DEALS and to begin ordering www.biosymph.co.nz
GilsoFlex Spraying Thinner is designed to reduce the viscosity of dense black bituminous/gilsonite-based GilsoFlex Roof Sealer & Paint for easy and effective spray application.
Ideal for spray applications (recommended maximum use: 10% thinner).
Made from a blend of Kerosene, Xylene, and other solvents
Also excellent for cleaning painting and spraying equipment after use.
0.5 Litre Spraying Thinner
Price: NZ$21.55 (incl. GST)
Product Code: GFT05
FREE delivery anywhere in New Zealand
1 Litre Spraying Thinner
Price: NZ$27.50 (incl. GST)
Product Code: GFT1
FREE delivery anywhere in New Zealand
4 Litre Spraying Thinner
Price: NZ$62.85 (incl. GST)
Product Code: GFT4
FREE delivery anywhere in New Zealand
Visit our website for COMBO DEALS and to begin ordering www.biosymph.co.nz
Holding a degree in Polymer Chemistry and Chemical Engineering, Pierre van Vuuren, the founder of Biosymph Ltd., has always been driven by a passion for innovation in the chemical industry. His journey began with the development of the highly successful BitPost Timber Stain and Preserver product line. Following that success, he expanded Biosymph’s product range, introducing other high-quality solutions, including the popular GilsoFlex Roof Sealer and Paint.
Pierre’s dedication to sustainability and safety led him to take on the challenge of replacing Creosote—a widely used timber preservative—due to concerns raised by MAF (Ministry of Agriculture and Forestry). Through extensive research and development, Pierre created a safer version of this traditional product, maintaining all of its benefits while ensuring a more environmentally-friendly and user-safe alternative.
Biosymph’s Growth and Customer-Centric Focus
Since its establishment in 2011, Biosymph Ltd. has experienced enormous growth, both in New Zealand and abroad. With a focus on delivering products tailored to the needs of New Zealand’s farming community, Biosymph’s products have gained a solid reputation for quality and effectiveness.
Pierre’s commitment to excellent customer service has led to a loyal and growing customer base, ensuring that every client has a positive experience with Biosymph. It’s this dedication that has propelled the business to not only thrive locally but also expand internationally, with export to Australia now underway.
Gilsoflex – roof sealer and paint
This is great for places that rain a lot.
I have a huge roof that had never been painted when I bought my home 3 and a half years ago and no one told me this, so will need to do two coats.
My house is a lot warmer with this on the roof so will pay for itself from having a warmer home.
Highly recommend for NZ weather conditions. :)))
Gilsoflex – roof sealer and paint
does 100% what it’s meant to
Posted by Steve Anderson on 23rd Apr 2025
Fantastic service and awesome products always.
Thanks Pierre
Gilsoflex – roof sealer and paint
Posted by Marcus on 24th Nov 2024
Great service from Biosymph – responsive service and very fast delivery.
This product is easy to work with, give a good mix with a paint/ plaster mixer and easily paintable with a large brush.
I also used this product with a spray gun which made it so much easier for a large area – can be used straight from the container as it’s already at the right consistency, no thinning required.
The finished look was very good and now happy the roof has a good layer of protection and seal.
Overall very happy with the product.
Roof paint
Posted by Andre on 25th Sep 2024
I am pleased with the paint quality.
It goes on easily it dries fast and one coat is what I like like as painting is not my thing.
Also mixed the paint to the colour I wanted .
Deck stain A+
Posted by Kevin on 17th Mar 2025
I recently had to refinish a couple of poorly maintained decks.
The finish chosen was clear natural.
Easy to apply. Easy cleanup. Fast drying. Looks great.
Roof paint
Posted by Andre on 25th Sep 2024
I am pleased with the paint quality It goes on easily it dries fast and one coat is what I like like as painting is not my thing.
Also mixed the paint to the colour I wanted .
For any enquiries, please fill in the enquiry form below, providing as much relevant information as possible. We will respond to your enquiry as promptly as possible. You can also contact Biosymph directly on the phone numbers below.
Phone: 07 829 8606
Phone: 022 607 6400
Email: admin@biosymph.co.nz
Address: 2287 Kakaramea Road, RD10 Whatawhata, Hamilton 3290, New Zealand